You can signup for Adsense with your Google Account. And can fillup the forms to continue.
In order to get Google Adsense approval, you need to have a site with Adsense code installed.
Before the approval process, you need to take care of the content on the website.
Make sure it aligns with the policies of Google Adsense.
If you keep these things in mind and do it properly. Adsense approval can be very easy.
Always remember to keep your website visitors happy, do not ever try to annoy them with annoying ads like popups. It can harm your website in the long run.