Vista - LINQ: Inner Join & Left Outer Join Q

I am having trouble doing an inner join and a left outter join in
LINQ.

Table A has a primary key PKA
Table B has a primary key PKB and a column with the foreign key PKA

I have no problem doing this inner join where A.PKA == B.PKA but there
is a third table C which has a foreign key PKB. The left outer join is
on B.PKB and C.PKB where the select includes count of C records along
with values from A and B.

I have the SQL but I can't get my head around how to do the outer join
and get the count. Could someone provide an example and/or point me to
a suitable resource? MSDN just seems to muddy the waters on this
topic.

thank you
A.G.