adding offset

With a TL062 it will be difficult, since you exeed the max. V rating. Either you will need a +/-18V supply, so your signal can be output with 15V peak. Or you can only have an offset range of +/- 2,5V with +/-15V supply. Since you do not show the actual circuit, we cannot say exactly what to do, but in a non-inverting application usually the inverting input is grounded. depending on your generator you might also have to do something with the remaining circuit dc-wise to overcome the added offset eventually.

-15V o |\\ | -|+\\ .-. ___ | >- 100k| |

I mixed up the inverting and non-inverting inputs, sorry for that.

i'll post a schemtic soon