|I assume by 'little memory' you mean your main hard drive is filling up and you want to put new software on the external. Some software will insist on installing on the C: drive, usually in the Program Files folder. With others you can specify where you want it installed.|
On your main drive you can do things like a disk clean up to get rid of temp and other files that aren't needed. You can uninstall any software you know you don't need. And you can move other documents--word files, music, picture and video files, most downloaded files--onto the external drive.