To raise the OG of the recipe (and therefore the potential ABV), open the recipe onto the design page. You see the slider under the material list for the recipes? Click on the slider for OG and you can enter the value you want. To get a higher ABV with most recipes, increase the OG by about 10 points (i.e. 1.040 >> 1.050). This will adjust your grain bill for the higher target extracted sugars. It will also have an effect on your bitterness. You can also adjust this using the same method as adjusting OG.
To keep the recipe relatively in balance, note the IBU:OG ratio and after adjusting your grains for a higher OG, adjust your IBU to the same ratio number. It's not exact in terms of same balance, but it will get you close enough.
If you want to adjust the FG of a recipe, you can change your mash temperature, increasing it to get a higher finishing gravity or lower to get a lower (dryer) finish. This will work within a range dictated by your malts and the yeast you choose. You can also add some simple sugars to the recipe to drive the FG lower as the sugars will ferment out completely or change to a less attenuative yeast for a higher final gravity.