Can i use these photos for my portfolio?

If I were to go to a Dodgers game and took pictures from the Left or Right Field seats, would I be able to use those photos on my portfolio or would I need to email the Dodgers organization to get there approval?
Thanks.
Also, besides sports i'm also trying to get into portrait photography, what 2 lens would you recommend for a Nikon camera?

American top-level sports are insane about their copyrights, trademarks and whatnot. There's even been cases where a fan that got a team logo tattooed got sued for it. So I wouldn't do it.

Portraiture. A 50mm is always a good start.

For a PORTFOLIO… I don't see why not. Using them for online commercial work may have issues, but a portfolio is personal to you, so I'd go for it.

For an APS-C sensor camera like a D300S D3100 D5100 or similar a 50mm lens will act more like a 75mm lens, and will produce slight perspective compression due to being on the telephoto side of 'normal'. This is flattering to the model as it will not accentuate facial features, in fact it'll do the opposite.
If you are using a full-frame camera, an 85mm f/1.4 lens is very nice and a good investment if you intend becoming a portrait photographer.
A good fast telephoto zoom like the 70-200mm f/2.8 is a great tool if you are into sports.

Contact a lawyer but my instincts are telling me that you do not need their permission for self advertising. Self promotion is not considered actual commercial usage as long as you don;t atemp to create a relationshiop between yourself and the team then you should be in the clear… But really, call a lawyer.

Of course, that also hinges on them eallowing photography at the game. Check your ticket.

Lenses for portraiture? 50mm f1.8 or f1.4. 24-70 f2.8.