Unless i am remembering wrong, aren't rasperries like blackberries?/ if so at the end of the bearing season you want to trim off the canes that bore.
then in the spring
trim back each side "arm" (can't think of the proper name) to about 12-18 inches.--(they will grow well beyond this length as the year progresses, so don't worry that you are cutting them too short) as they grow you can 'train" them up to a trellis. i always thinned out mine-but i am sure I lost lots of berries with doing that---but the ones I got were bigger---so i did not worry.
also they tolded us that IF the main cane was more than pencil in size they would not do any good---I found that not to be the case--but whenever I wanted to thin out a cane or 2 I chose the thicker main canes. -----they did seem to snap right out of the ground---
i say Raspberries are like blackberries because the home extension berry class i went to to learn how to trim Blackberries actually used raspberries in their demonstration
what Mark said about the weeding & such is true---I always weeded & heavily mulched my plants. (i used grass clippings) Adequate water is needed to ensure a good harvest.