It sounds as if your dog has developed conjunctivitis, which is an eye infection. You can clean the pus off your dog's eye with a warm washcloth. You can also flush your dog's eye with sterile saline solution like contact lens wearer's use. This will help remove any possible foreign material that might have gotten into the eye.
I have to tell you that you should have your vet look her over in order to get some medicine for your dog. Frequently an antibiotic eye drop is given for this condition. Sometimes Terramycin Ophthalmic Ointment is used for these problems. A quick search should bring up numerous sites with this product.
You can read more about canine conjunctivitis here.
Canine conjunctivitis is a common eye problem. It can happen by itself or indicate an underlying problem. Finding the underlying problem can prevent future bouts with conjunctivitis. Underlying conditions that can cause conjunctivitis is KCS (dry eye, insufficient tear production, upper respiratory diseases such as kennel cough. Usually with respiratory infections there will also be coughing, sneezing, nasal discharge, fever, lethargy and loss of appetite. Conjunctivitis can also be cause by a foreign object in the eye or chronic irritation from a development problem of the eyelid and lashes where the lashes rub constantly against the cornea.
You should have your dog seen as eye problems such as you are seeing are frequently the result of an underlying cause and can rapidly progress to the point where the dog's eye sight might be compromised. I'm going to give you a site that goes over eye problems for you to look at as well.
I hope this information is helpful to you.