How do I add flavours ie banana, cherries, oak chips etc?

Still getting my head around this as I'm new to the game but when do you add the fruit to get the flavour, if at all?
Love cherry beer so would I just throw loads of cherries in my fermenter or is this the secondary stage?
Any tips would help! Cheers!

Probably better luck if you'd posted in the beginner's forum but here's my 2 cents:

fruit is generally best added during secondary (it's what secondary is for, otherwise not generally needed). the yeast has a tendency to ''scrub" the flavors out of the finished product so you want to do it after primary fermentation is mostly done.

depending on the style, you can get banana esters in wheats depending on the fermentation temperature. otherwise, add the puree to secondary (same with cherries). fruit's got a lot of bugs on it, so a puree followed by a quick stove top pasteurization is best. my lhbs has canned fruit puree for wine kits, if you have that available that'd work. another option is to purchase frozen fruit (freezing damages the cell walls, allowing more extraction I believe). depending on the fruit, you may need to add quite a bit to get the flavors to carry over to the finished product.

is there something specific you're wanting to do/aim for?

Usually any fruit additions are added to a secondary vessel and your beer is racked onto it. Usually you will get a small amount of fermentation and should leave it to sit at least a week. Alternately you can use a flavoring at bottling or kegging time. I, personally, can tell the taste of a flavoring and will never use them. There are fruit extracts that are very good, although I haven't used them, I have had meads flavored with them. These were recommended to me for a Mango Wheat beer I did last year, but I opted for using the fruit instead.

Nothing In particular, I was just struggling to find any instructions on it. Thanks for the insight, have a better idea of it now!

There really is no great answer and methods vary, so I did some experimentation with fruit flavors.
I made a peach cream. I pureed the peaches, added some vodka then froze them for a few weeks, then added them to the secondary. At first it was super tangy, but after lagering for a month or two it really mellowed out and was good.
Recently i made an orange Kolsch. I boiled oranges with the skins on along with my hops and added the orange vodka puree to help cool the beer before primary. Of course this clogged all of my hoses and was a pain. However, 8 weeks later i have an awesome orange tasting Kolsch.
If you want a banana flavor i suggest using a yeast to achieve that flavor. If you want other flavors the easy route is to add a syrup or concentrate before bottling, but i agree with mouse that you can tell the difference. It mostly flavors the beer instead of being a part of the beer.
For my peach cream beer i actually made 10 gallons, but 5 with peaches and 5 without. Its a really neat way to see how drastically the fruit addition influences your brewing experiment....and you have more beer.