You should be able to edit the content of the pages even now. Keep in mind a couple of things:
1. The base language of the site is English. There are a number of translations in place but it appears they do not work in reverse - rendering items in English when a contributor uses another language to enter them. This is especially true of the "General Information" section of the page. If a German user puts "Violine und Klavier" in the "Instrumentation" field it will eventually be changed by an admin to "Violin and Piano" in order for it to be (hopefully) rendered into the equivalent terms in other languages (depending upon how extensive and up to date the translation matrices are).
2. Certain fields in the "General Information" section are actually 'read' by the system - the date fields in particular (first performance, composition and publication). The system needs the year to be first in order to read it. Thus if a work was first performed on June 27, 2012, it should be rendered 2017-6-27. Since exact dates of composition and publication are less often encountered, the year should appear first in those fields aslo.
3. Please put your own name in the publisher field when uploading. Making an item available at IMSLP meets the legal definition of "publication" under most copyright statutes, because a file is actually duplicated every single time someone downloads it.
4. We do have rules about page layout, treatment of arrangements, etc. that you should become familiar with before embarking on any edits. Here is the start of the Manual of Style
. One of the best ways to learn is to review your own pages after they have been tagged for copyright approval. The copyright taggers usually will modify things as needed on the page to bring them in conformity with the page layout guidelines, etc.