So, I quite enjoy Double headed giant,most often I play and green blue midrange, but on ocassion I play lockdown.Now I'm wondering if I play a card likeghostly prison or Propaganda does the effect affect both me and my teammate, or just me, if just me how does that work?
If here is a cost to attack one person, that cost needs to be paid to attack the team. Note that with the two cards you listed, there is no cost to attack planeswalkers.
However, if you control Sphere of Safety the opposing team still does not need to pay the cost to attack a planeswalker your teammate controls.
Players in Two-Headed Giant attack and are attacked in teams owing to the shared life total. Any creature that is attacking your team is, by definition, attacking both you and your partner at the same time. Therefore, Ghostly Prison and company will always apply.
Even in Two-Headed Giant (not: Double-Headed Giant), Propaganda and Ghostly Prison provide only that creatures can't attack the controller of either permanent ("you"), not any other player, unless certain costs are paid (C.R. 109.5).
In general, the word "you" on a static ability (such as those of Propaganda and Ghostly Prison) means only the controller of the object where that ability appears (C.R. 109.5). Nothing in the rules for the Two-Headed Giant variant or the Shared Team Turns option changes the meaning of "you" (review C.R. 810 and 805, especially C.R. 810.5). See also this thread.
While this is technically true, it doesn't answer the question (and seems to imply the wrong answer). Yes, Propaganda does not change who "you" is (are?) but this rule clearly states that any restriction about attacking a specific player applies to attacking the team:
810.7c. As the declare attackers step begins, the active team declares attackers. If an effect of an object controlled by a defending player prohibits a creature from attacking him or her, that creature can't attack the defending team. The active team has one combined attack, and that set of attacking creatures must be legal as a whole. See rule 508.1.
Example: One player in a Two-Headed Giant game controls Teferi's Moat, which says "As Teferi's Moat enters the battlefield, choose a color." and "Creatures of the chosen color without flying can't attack you." Creatures of the chosen color without flying can't attack that player's team.
EDIT: I see your post was updated while I was typing mine. Ward of Bones (referenced in the linked thread) is not the same as this situation. The fact that Ward of Bones doesn't care about your teammate is irrelevant for this question.
As of Dominaria, creatures can now attack individual players in a team in Two-Headed Giant as in any other game using the shared team turns variant (C.R. 810.7, 805.10a-b).
Therefore, now, in a Two-Headed Giant game, if a creature isn't restricted or forbidden from attacking a player, that creature can still attack that player even if it is restricted or forbidden from attacking that player's teammate (such as with Ghostly Prison or Sphere of Safety).
It's still the case, however, that in general, the word "you" on a static ability (such as those of Propaganda and Ghostly Prison) means only the controller of the object where that ability appears (C.R. 109.5). Nothing in the rules for the Two-Headed Giant variant or the Shared Team Turns option changes the meaning of "you" (review C.R. 810 and 805, especially C.R. 810.5).
However, if you control Sphere of Safety the opposing team still does not need to pay the cost to attack a planeswalker your teammate controls.
Example: One player in a Two-Headed Giant game controls Teferi's Moat, which says "As Teferi's Moat enters the battlefield, choose a color." and "Creatures of the chosen color without flying can't attack you." Creatures of the chosen color without flying can't attack that player's team.
EDIT: I see your post was updated while I was typing mine. Ward of Bones (referenced in the linked thread) is not the same as this situation. The fact that Ward of Bones doesn't care about your teammate is irrelevant for this question.
Therefore, now, in a Two-Headed Giant game, if a creature isn't restricted or forbidden from attacking a player, that creature can still attack that player even if it is restricted or forbidden from attacking that player's teammate (such as with Ghostly Prison or Sphere of Safety).
It's still the case, however, that in general, the word "you" on a static ability (such as those of Propaganda and Ghostly Prison) means only the controller of the object where that ability appears (C.R. 109.5). Nothing in the rules for the Two-Headed Giant variant or the Shared Team Turns option changes the meaning of "you" (review C.R. 810 and 805, especially C.R. 810.5).