Primaries are the pre-election elections in which the eventual nominee's from each party are chosen.
I'd suggest trying to do a little research on both the election process and the candidates themselves to help determine who you should vote for. Asking an open forum if you should vote for a candidate doesn't seem like the best way to reach a thought-out conclusion.
In response to what you've heard about Trump:
"he's a strong guy on the issues". The only issue he appears "strong" on is immigration. That isn't to say i agree with his position, only that he has a strong stance which resonates with many on the right.
"is he a good Christian?". Doubtful. He refused to give his favorite Bible verse, says he's never asked God for forgiveness, I believe that he's a social Christian in that he identifies with Christians, but doesn't seem to study or espouse Christian theology.
"will he fix the global economy?" No he won't. Neither will any of the other candidates for that matter. He is lauded by many on the right as a "great businessman", but the reality is, he inherited a tremendous amount of money, was given a position in a successful enterprise by his father, and has done adequately as a businessman. He has declared business bankruptcies 4 times, which negatively impact his investors ( the kind of thing which weakens the economy). It's hard to say how he'd impact the global economy, although he's hinted at violating several international trade agreements that the US is currently in. If you believe it should be "USA vs the world", then he might be your guy. If you believe that democratic civilization should be working together, than he's probably not your guy.
