There are a couple of ways to go about it. A common way is open party-list proportional representation. Each party puts forward a list of candidates. The number of elected candidates depends on the proportion of votes with respect to the total (e.g. 10% of votes with 100 total seats means 10 seats for that party), where those candidates who received the most votes within the party list get elected.
And the party chooses the reps, or how is that done?
There are a couple of ways to go about it. A common way is open party-list proportional representation. Each party puts forward a list of candidates. The number of elected candidates depends on the proportion of votes with respect to the total (e.g. 10% of votes with 100 total seats means 10 seats for that party), where those candidates who received the most votes within the party list get elected.