First thing to do is to open gmail account Here

Login into YouTube using the above account that you created.

On the YouTube dashboard click on your avatar image. Note make sure you turn your browser to laptop view if you are using mobile.

See the image below

Click on my channel or creat studio for you to be able to create new channel , skip this if you have channel before.

See images

Now click on my channel it will direct you to where to create channel if you don't have any.

see images 

Complete the process by following the images below

Congrats done creating your first channel.

From the image above click on channel . See the image of next step after clicking on channel.

Click on monetization and follow the instructions from the images below

Login with your email account the image above.

Follow next step by seeing more images.

Image above is the final step , congrats your account is under review , you have chance to be approved . 

Next article will be what to do if Google adsense have finally approved you.

find this helpful keep sharing it.