SQL commands in VB

Hi,
I have a fully functional Acess database (albeit very simple)
I want to put a VB front end to it. (for my experience and learning as much as any other reason)
I have a litany of problems/questions i will try to ask as few as possible here, if i need to break them up i will do so, but i dont think any of them would pose much of a problem to some of you guys.

First, how do i run an SQL command in VB?
In Acess i used to use the DoCmd.
I have a table call it tlbUsers, it contains the user ID and first and last name and Password fields.
For my login dialog i have a combo box that the user picks his ID from, in Acess it is very simple to add columns to the drop down i.e. display the ID, FirstName, Lastname on each row. I dont think there is such a simple control in VB (i have downloaded some examples and got them to work but not to my satisfaction). as well as that they were too complicated for what i need.
It would suffice for me to concatenate the columns and display one string when the user drops down. How can i do this?
I know how to concatenate in SQL so i thought:

Declare a new string NewString
NewString = select statement concatenating the 3 column values and then
MyCombo.DisplayMember = NewString
MyCombo.ValueMember = "ID"

so when the user picks his name the combobox text shows only his ID.

Then i want to search through the table where ID = selectedID and compare the passwords.
(this is my btnOK_click event)

So how do i run the SQL?

Thank you for reading - i hope someone can help.