Hi Moonlight, you really need to understand how you want your bait to behave as you will not always want your line to sink, as a generalisation if you are fishing still or slow moving water a bottom end only float is preferable ( waggler ) and if you are fishing your bait close to the bottom you would probably want your line to sink, try keeping some cheap washing up liquid with you , overcast and wind back in holding a soaked sponge against the line, remember to treat the length that runs along the rod !. when you cast feather the line as it lands dip your rod tip under the surface of the water and a couple of quick turns of the handle will sink the line,set your rod to sit on your box and rod rest with the tip just under the surface while you wait for any bites.
for faster water a stick float or similar may be best and for this you would normally want the line to float.
Float fishing is a rewarding method and takes lots of practice,try and get hold of " float fishing by Billy Lane " from your local library ( or e-bay )a bit dated now but is really excellent .
Good luck and persevere !