¿Esto suena natural? You can get 10 tickets every month.
Your posted questions will appear at the top of the question feed.
You can select which question to use a ticket.

1. "You can get 10 tickets every month." -> "You get 10 tickets every month."

"Can get" means that the user must take some action to get the tickets (like もらうことができる). If the system is automatically giving the tickets to the user, just say "get" or "receive."


2. "Your posted questions will appear at the top of the question feed." -> "Use a ticket to put one of your posted questions at the top of the question feed."

This change isn't strictly necessary, but I feel it's more clear this way. In the original wording, it's not totally obvious that the second sentence is related to the first. Of course, the third sentence implies that this is the effect of the tickets, but it's better to make the meaning clear throughout.

3. "You can select which question to use a ticket." -> "You can select which question to use each ticket on."

The verb "to use" can work with or without an indirect object, but if you have one (and we do in this case: "question"), then there needs to be a preposition ("on") linking them.
An alternative wording is "You can select on which question to use each ticket." Some grammar sticklers prefer this placement of the preposition, but it sounds much more "stiff" and very few people speak this way. My vote would be against this.

"Each": I changed this because it sounds more natural to me. It's tricky to get situations like this right, where there are multiple objects and we're describing relationships between them. There is a one-to-one relationship between tickets and questions, so it may seem natural to use the singular ("a ticket" and "question"). But there are multiple tickets, and multiple ticketed questions. I think the sentence needs to acknowledge this plural somehow, otherwise it sounds a bit like the user only selects one question. Another way of accomplishing the same thing would be to say "which questions to use tickets on."
This part is complicated and only has a small effect, so if it's confusing then I would just ignore it.