Usually some teams have many different uniform choices that they can choose from and I was just wondering who decides what they are going to wear for that day?

Home team decides white or colored.
Special Jersey such as throwbacks are decided and or approved by the NFL.
Dallas Cowboys almost always wear white because they wear them at home and away cause most teams wear colored at home.

Home team wears colored jerseys; away team wears the white jerseys. Reverse of baseball.

The Home team calls what type of jersey they wear and what the oppent wears opposite to that. Home team can choose to wear home or away jersey.

I thinks Paul Taglibue decides it. Hes the man behind the NFL. But why do the Cowboys wear there white uniforms for home games?

well it depends, sum teams have just the home (colored) and away (white) jerseys. HOWEVER, there is sum alternate home jerseys which is usually worn on the day of fan appreciation day. For instance, Philadelphia Eagles normal home jersey is green, but the alternate is black (usually only worn once a season).

I believe the home team gets to decide what type of jerseys they are wearing and the visitors have to wear the opposite.

The home team for each game makes their choice and that helps the visiting team know what they will wear.