I would like to create a statement where if specific fields are true, then I get a specific return type. 

For instance,   I have a field titled "Do you own your own home?" with dropdown list as "Yes", "No", or "NA". Another field titled "Do you have an existing mortage?"  with dropdown list as "Yes", "No", or "NA",  and a field titled "Est. Credit (FICO) Score" with "Number" entry. 

I would like to setup a formula titled "Lead Rating" where if the following conditions hold true, then a specific 'rating' is returned.

In English/semi-Zoho language it would look like:

If(${ Leads.Do you own your home?}, 'Yes') And (${ Leads.Do you have an existing mortage?}, 'No') And (${Leads.Est. Credit (FICO) Score > 650), Return 'HOT'

Additionally, I would like to further the formula so if the opposite is true then a the formula would return a rating of 'POOR'

Please help with a step-by-step guide on how to set this up, along with syntax and correct Formula Return Type needed. 

Thanks