Right now in league, there are very few champions that I'd consider terrible, veigar isn't one of them.
How experienced are you with mobas? I'll give you a generic explanation of Malphite's role. He is an initiation tank. His role(usually) is to start fights by ulting onto priority targets. Once he blows his ult and is in the fight, he only really has two choices. First choice is to disrupt the enemy back line as much as possible, to buy your team time to lay some damage down on them. Second choice is to turn tail and get out, but that's down to your discretion, and is a decision which you will learn to make after you are more familiar with the game. The real game doesn't start until you're level 30, so just have some fun for now and try to learn the basics
If you're NA, add my smurf, we can play a few if you want. My smurf's summoner name is Madiqis Aard
Since you just started, that means the people you play against just started as well. I find that watching some games from pro players on youtube helps you see what you are supposed to do.
for example, go on youtube and type challenger malphite top and you'll find some videos of people playing malphite and you can see how to play him effectively. Or you can just frolick about until you hit 30. Try and find your comfort champs at this point as it lets you climb much easier.
Also champs that have higher ip cost dont necessarily mean they are better, it just means that they were released more recently.
Post game screen for anyone who cares
I've never played him because he doesn't seem like the type I would like. Whats he like?