Hello chenti
If you want to apply for ews in engineering you need to mention it in your application of examination (I.e. JEE)
and you need an income & assets certificate by authority.
You don't need to upload certificate online like in JEE mains.
But sometimes you do need to upload the certificate like in JEE advanced.
Also in some colleges you need to submit the certificate at the time of document verification in the college.
I hope it helps
Best of luck

Dear aspirant,
First of all you will have to proof that your income is below a certain government specified level for that you need an income certificate. The following documents are needed for income certificate
You should have an ID proof which can be a copy of Adhaar card, Pan Card, Driving License, Passport or a Voter Card.
After you get the income certificate you must file an application for the ews category. Please do check this procedure with your district office if they issue a ews certificate or the income certificate will work as an ews certificate. In any case generally the following applies.
While filling the Application form, the applicant needs to submit Residential proof which can be anyone out of these options Water bill, Electricity bill, Telephone bill.
Incase there's any step I missed out feel free to correct me .
Thankyou

Hey Chenti! Economically Weaker Section in India is a subcategory of people belonging to the General Category having an annual family income less than ₹8 lakhs and who do not belong to any reserved category such as SC/ST/OBC. You will have to generate the ews certificate using which you can register for counselling.