I'm a beginner at landscaping and need some help. I have an area that's about 5' X 5' in the corner of a fenced backyard (6' tall fence). I live in a townhome, so I'd like to plant a tree that will grow to about 15-25' to block out some of the view of the homes behind me. For that reason, I'd prefer something that's fast-growing and an evergreen/conifer, so that the view is blocked year-round. I would also prefer something that is tolerant of pruning, as I'll have to make sure it doesn't grow into a nearby path and I may want to prune off lower branches in order to plant flowers around the bottom of the tree. Any suggestions? Thanks!