It's pretty hard to explain in writing how to apply a tip correctly......
Not easy without visual aids.............
Gel Enhancement tips, are applied in the same way as any other system....
Normally, the tip is applied from the front, and rocked on.............
On a suitable nail, preblend the tip, reduce the well area............
The white bits you are asking about, are usualy bits of the tip that are not adhered to the nail correctly..........or the tip is the wrong size, maybe a tad to big and the tip over shooting the nail plate on the sides???
Tips come in various sizes, and sometimes need tailoring to fit the nail plate ...........
On a nail biter it's a bit more tricky...you might just need tad extra well area, to build a visually correct and stronger base for the product you will be using, as your chosen overlay........and one to one training is the best way to cover this.................
If you do a search on this board you will find some posts covering this......
Tip application and blending are one of the first things you should learn on any good Nail Training course.....
Who are you training with ???
Maybe some one to one with your tutor will be far better then going it alone........as she will be able to show you how to, then watch you doing a nail....... then either say "brill" or will tell you where you are going wrong.......
Keep at it girl...............
You will get there...........sooner then you think