Hello..!!

You need to do registration for choice filling. Visit their official website https://fe2019.mahacet.org/staticpages/homepage.aspx

Then do the registration.

Then report at facilitation centre, and verify your documents.

Finally, you will have to submit list of colleges in order of preference.

For more information: https://engineering.careers360.com/articles/mht-cet-counselling

Hii dear, 

It would be easier to help you  if you had mentioned about the exam for which you are asking the choice filling process.

I will tell in general -

Step 1: Visit the official website of the exam portal site 

Step 2: Click on seat allotment link or tab for your courses

Step 3: Enter your examination application number and captcha code and submit

Step 4: An online form with the list of colleges and courses basis your eligibility will be displayed

Step 5: Select your preferred choices and submit

Step 6; Also take a print out of the selection list for future reference 

Hope this helped. 

You can ask if further queries. 

Good luck.