Fungus?!

A couple days ago, I noticed that I had this sort of fungus, sort of thing near the ring of my penis.
It's a yellow, and dark brown color. I don't know what it is; I'm very worried.
Is this a STD, or something?!

[Dr_Aparna]

Hi,
Without regular cleaning, a build-up of a whitish-yellow substance known as ‘smegma’ can occur under the foreskin. Smegma can look like pus to the untrained eye.
Bacteria, yeasts, stale urine and sloughed skin cells rapidly accumulate under the foreskin to form a white, smelly, cheesy substance known as smegma. Smegma that is allowed to build up can cause irritation and soreness.
Inflammation of the glans (glands) is known as balanitis.Balanitis causes symptoms of redness, soreness and itching on the end of the penis.Little red spots appear and there may be a build-up of yeasty smegma under the foreskin.
Balanitis is largely preventable by proper hygiene and frequent washing under the foreskin. In mild cases, simple bathing with salt water (saline) twice a day will cause rapid resolution of symptoms. Stopping using soap may also do the trick.
Some cases of balanitis are also due to detergent allergy or irritation.
Moderate to severe balanitis due to thrush needs treatment with an anti-fungal cream (e.g. clotrimazole). If the infection is bacterial, antibiotic cream or tablets will quickly solve the problem. If balanitis is severe, with gross swelling of the foreskin, or if it is recurrent, circumcision may be required.
ref:http://www.tiscali.co.uk/lifestyle/healthfitness/menshealth/part1_1-2.html