Start with logging in to your web account at My Ework.
When you're logged in, click on "New Profile" under the heading "My Consultants / Consultant Profiles". Fill in your contact information and upload your resume for the current profile you are applying for.
Add a extensive motivation. In My Ework you can read that the motivation shall be 5 - 8 lines, but we prefer that you are more profound than that.
If you can't find the apply button on the interesting assignment, please make sure that you have created a consultant profile and that your profile has the skills required for the assignment.