Custom Number Sequence need to display in my new Form

I searched all the blogs and tried several steps given by many developers but could not get the number sequence generating in my form. 

My Requirement is :

I have created a table with 14 fields and one of the field is RFI Number.  I need to generate my own sequence number for this RFI Number field and that needs to be associated to my New Form.  So that every time I insert a new record from form, new sequence number should be generated and saved in database.

I am new to DAX so I am not sure about the parameter table and how to create that.  May be this is where I am lacking and so I am not able to generate the sequence numbers.  Please provide the exact and complete steps.

Thanks in advance!!