Go to the signup page and choose "I'm looking for work." You'll need to verify your email address before you can finish creating your account. During signup you'll pick one or more sectors you're interested in - these drive which jobs get matched to you, so pick every sector that genuinely applies.
If a sector you picked requires a license or certification in your country, you'll see an upload field for it during signup - but this is optional. You can skip it and add it later from your profile once you have the document ready.