Preseed? Advice plz

So.. I'm planning on buying preseed because of the good reviews but I have also seen a few negative ones.. I just wanna know if anyone here has used it? And did anyone have any successful stories? I've been ttc for a year now..

Plus how would I use it.... does the whole stick go inside or like halfway?

Update aww thanks everyone for the comments .. I guess I will but them soon and give it a try