hi, the last date is Nov 10 so I see your urgency. Dont panic please. The steps to fill the form- you need to keep scanned images of your photo, signature ready before filling the form. If you are in class 12, then a certificate from principal will be needed. You could get that signed tomorrow if you dont have it. Also category certificate if you are applying under reserved category. Class 10 certificate scnned copy for date of birth proof. For photo and signature it should be in a file 5KB to 50 KB in JPEG format. For the certificates, pdf format 30 to 500 KB.
Since you have to pay online, keep the debit or credit card ready or even net banking details. Now you have to register firstand after you register, you can fill the form. The form is easy to fill. check this article- https://engineering.careers360.com/articles/uceed-application-form. It has all details with screen shots so you can follow it easily. Write back if you have any further doubts. I shall be only glad to help out.