Then you need to explain things better.
Are these two homes on one lot? If yes, you will first have to subdivide before you can sell one. If no, go to next question.
Or is each home on its own lot but both properties are on one deed?
The house you live in is your "main home" (that's what the IRS calls it) for the purpose of the capital gains exclusion.
The house next door that you store stuff in is not your "main home."
Your "main home" probably qualifies for the exclusion if you have lived in it for at least the last two years. To get the capital gains exclusion on the second home you will have to sell your "main home" and move in to the house next door and live there for at least two years before it qualifies for the capital gains exclusion.
The above example is overly simplified and you can get more information from IRS Publication 523 - Selling Your Home:
https://www.irs.gov/pub/irs-pdf/p523.pdf