Hi, welcome!
First off, I should say that I'm probably not the best person to be giving game advice, as I'm really more into
40k for building/painting models than actually playing the game...I've only played about 10 games so far myself.
anyway, with what you have, I think you'll be able to play some "Kill Team" games - which might be a good way to start anyway, honestly
however, for normal
40k games, you will need to at least add one more box of boyz to your collection (or a box of gretchin, but boyz are probably a better choice)...because the total bare minimum for a normal army list is 2 "troop" squads and 1 "
HQ", and you currently only have one troop squad worth of boyz...but, when you get that second box of boyz, you should be able to start playing ~1000 point games using everything you have, and then you can slowly expand your army from there
now, I can't really tell you much about how "good" the stuff is, due to my lack of personal experience with the game...but, fair warning, orks are probably one of the least competitive factions in the game, so really, no matter what you include in your ork army, if you're facing one of the stronger factions, you're probably in for an uphill battle, that's just how it is I'm afraid
...don't let that discourage you from orks though! they are still a lot of fun to play, they have a lot of the most characterful models in the game, and they also give you probably the most freedom of any faction when it comes to modelling, conversions, kitbashes, scratch-builds...they may not be the best at winning games, but in my opinion they're still one of, if not the best faction for pretty much every other reason
...and really, because they're not that strong, that just makes it even more satisfying when you do win a game!
some things you may want to add to the army later on though, because I've always heard good things about them...meganobz, warbikers, tankbustaz...they seem to be about the orks best units, game-wise...and more boyz, more trukks, and more mek gunz...they'll always come in handy
...also, I've gotta suggest looking around on ebay...a staple of a lot of ork players army core came from an old 2-player starter set called "Assault on Black Reach"...it was an orks v space marines box, and the ork half contained: a warboss with a power klaw, 5 nobz, 18 slugga/choppa boyz, 2 boyz with big shootas, and 3 deffkoptas with twin-linked rokkit launchas....now, if you look around on ebay every week or so, you're bound to find some of that stuff floating around, if not now, then probably fairly soon, they're quite common, and they're usually quite a decent price too
...the deffkoptas are great, the warboss is a solid
HQ choice, and ork armies always need more boyz
...the nobz aren't that great though if I'm honest.
oh, and the blood angels stuff...yeah, I really don't know much about them, but again, you might be able to do some kill team games with them...but otherwise, you definitely need another
tac squad, and probably a bunch more stuff...that's probably a decent start though,
tac squad is compulsory, and fairly solid, and terminator captains are generally a decent
HQ choice I think
...it's good to be green! 
