How to submit documents to IT department for returns filed

Respected Sir/s, I have submitted my IT return for FY 2017-2018 on 31st Dec 2018, this was late filing of tax, with penalty. I have shown Interest of Rs 2 Lakhs and Principal of Rs 74000 for the entire FY 2017-2018. The property was taken possession of in June 2017, though they had started giving possession in March 2017. I did not claim other category for property below 50 lakhs , since I didnt understand the section well. I filed taxes myself on incometaxindia website. I am a salaried person with taxable income less than 5 lakhs, including exemption availed for Home loan. 1. My question is how do I submit my documents to Income tax department, for them to verify the correctness and avoid getting a notice on this tax returns? Also I am entitled for a refund, but I am not sure if process is done correctly by me, since there was no way of submission of documents. 2. What are the possible documents I should submit? 3. Is there a possibility of any other problem arising from this? Thank you so much for your response in advance.