To file your ITR, login to your IRIS using your credentials.
Under decleration tab chose (Return/Statement) and select (Normal Return (Ind/Aop/Coy) and then select the year, i.e., 2025.
Here is how you can proceed with ITR from IRIS.
Tip: Before this, make your work in excle file and do all reconciliation b/w (Income/Expense, Inflows/Outflows). After this you just need to copy and paste your work to the IRIS portal.