oneToMany or manyToOne Doctrine2 relationship

oneToMany or manyToOne Doctrine2 relationship

I have the following situation.
I have a clients table and services table.
case 1 What I want is to know how to make a submit form in Symfony2
(actually I think that if you can guide me only in YML mapping is enough)
that can CRUD a clients entity, which it can has X services assigned to
it.
clients table only has id and nombre columns, same as services.
case 2 Then, once this is done, I have a new table called task this new
table needs to have the following:
A client for the task. A service for the task, which, at the same time
needs to be assigned to that client, so it is dependent from client select
box (I can make this with jQuery) And some oneToOne relationships which
are actually working very well.
If the task has more than one client, it would be great if I could add on
the same form using prototype with forms collection or something a new
client, and of course, a new service if needed... But this is totally
optional, what I'm really lost is in case 1, because I think if someone
could help me with case 1, case 2 will be easy to make on my own...
And of course, I don't know what to use, oneToMany or manyToOne in both
cases...