Sequential work-flow to fire when a new user is added to sharepoint site

See more:

SharePoint

Hi
I am new to share point work flow in visual studio.

I have a set of code** ready.
I need to execute this code through workflow
When a new user is added to share point site.
OR
after every 10 minutes


Can I use Sequential work-flow in Visual-studio for this?
or which type of work suit for this?
Where should I add this code in work flow?
Can any one explain me in detail.



**What does code do?(This code is ready: Just I am explaining to you)
-------------------------------------------------------------
There is list called Person with column PersonEmail , UserLoginName etc.
Person in this list may or may not be a user of the site.
If he is not a user of current site "UserLoginName" column will be blank.

Whenever a new user is added to share point
this code will execute to check(using e-mailID) the newly added user is a person in the list with "UserLoginName" column blank. If so It will update the userLoginName column.