To submit work to QSpace, login into QSpace and then navigate to the Communities&Collections page to select the Community you belong to.
Each user has specific permissions as to which collections you may submit to. Open up your collection homepage and click on "Submit a new item to this collection" link.
Alternatively, you can click the below link to select the collection for which you are permitted to submit your work. This will direct you to the item submission page to submit your work.