How to create tables with geometry in Postgres?
The simple answer is: 

create table points ( p POINT not null); 
create table lines ( l LINE not null);


Then inserts look like this:

insert into points (p) values (POINT(1.2, 123.1));
insert into lines (l) values (LINE(POINT(1.2, 123.1), POINT(-5, -123)));


You probably want to build indexes if you want to have some lookups on them. Also a primary key may be beneficial.