If it is not calibrated, that will only be off a little, at this point it is more important to learn how to read it. Get a test jar, put must into that to get a reading.
And like I say, a wine recipe is ONLY a guidance NOT a rule. To make a fruit wine, use at least 5# of fruit per gallon, have a sg of around 1.080, check your acid and add acid blend if needed, add tannin if needed, add yeast nutrient, k-meta, wait 24 hours add yeast. Normally I use Lavlin 1122 for fruit wines.
Stir daily, rack to carboy when sg is below 1.010 or snap down the lid and add an airlock at this point and let it ferment to dry.
To backsweeten your wine, make sure you add k-meta and sorbate first, wait at least a day, some wait a week, then I take some of the wine from the carboy and add sugar to that, warm it up to dissolve the sugar, add back, taste, if you like it, take a reading so you know what sweet level you like to be able to do this another time.
