Dear Jeanagh~
Welcome here. It's a little difficult to give you a specific answer to your question as we do not know what you have done already. I presume you are talking of mental illnesses.
The normal way to gain a diagnosis is to see a GP and set out in detail you symptoms, feelings and life history and ask to be diagnosed. This may well lead to a referral to a psychologist for therapy or a psychiatrist for further diagnosis or other treatment.
If you have already been down this path and feel your illness has not been accurately recognized then seeking another opinion form another medical practitioner is quite acceptable.
Should you wish background information on depression or anxiety then The Facts menu above can be of assistance. It has quite detailed listings of symptoms and treatments. The other thing to do of course is browse around this Forum and see how other people fare.
Please feel free to talk more, perhaps you might like to give an idea of your circumstances and the problems you face.
Croix
