Using
#links a {clear:left;float:left}
floatwill allow the size of the link, and clearwill prevent the links from being on the same line.
You may need to add clear:leftto the container #linksdepending on your design.
EDIT
A small tutorial since you asked:
: . . .
. .
<a> . , , .
float , . float / . .
( ).
display:block float: .
display:inline-block, , ( ).