collision inside a map?

maybe my questioin is wrong, pease clarify.

i have created a 2d scrolling map (based on tiles), now i have to assign collisions to the walls and some things that exist in the map i created, can i assing collisions in this way or do i have to add the walls and objects manually via programming?

because i know that imagescollide if i have the handle and test it against the character, but i dont know how this thing works in a map file.

thanks for any comment.