It should be sticky and bubbly after the first rise, this is normal for sourdough.
You should then tip it out onto a board and add a good handful of flour and fold this in. At this point enough flour should be used that the dough becomes dryer and more like normal bread dough (not very sticky).
If you need to, add more to get it to this consistency. Flour brands and types differ so you may need to adjust, just as you would with any baking recipe.