This sounds like someone needs some basic training on tube repair. Suich things used to be passed down the generations but the emasculation of the male has stymied this tradition.
First of all, you need to find the leak. This is easy enough with soapy water, a large body/container of water or some slight over-inflation. Mark the leak with a pen, paint, stick pin or other method.
Tubes are made in a mold and are coated with mold release agent. This is a wax that will prevent glue from adhereing to rubber. If you had a good solvent, you could wash it away but this is expensive so the next best way to remove the release agent is mechanical abrasion. Sandpaper works but in olden times, a "nutmeg grater" was also used. If you are in the shop, a rotary abrasive tool, known in the Colonies as a Dremel Moto Tool, can be a real time saver.
In good light, note the sheen and colour (spelling for you loyalists) of the tube. Its a graphite grey-black but when properly prepared for glue, it will look like fine jet-black felt. 6x felt. Also, any mold seams should be removed in sanding. Brush the crumbles away and note the location of the hole. Make sure the sanded area is LARGER than the patch and centered on the hole.
Now its time for cement. You only need a VAPOUR thin but even coating, just enough to "fill in" the sanding profile, nothing more. Thinner is better. If the cement will not flow, its will make a poor patch job. Use a toothpick to quickly spread a small drop of cement over the entire prepared area. Let this dry for at least 5 minutes. Its fast drying but just be sure. Keep all dust and dirt off the drying cement.
Now its time to re-find the leak. inflate the tube a bit and you should see the leak as the cement will turn white as it stretches. Let the tube deflate and remove the thicker, aluminum foil cover on the patch. Leave on the protective,clear backing as it helps to keep your fingers off the clean, adhering layer. Some patches will have a base layer of partially cured red/brown rubber, capped by a vulcanized "strength" layer. Red goes to the tube. Carefully center the patch over the prepared area and push firmly from the center to the edges.
If the prepared area is larger than the patch, you can safely pull the clear film off but this is not needed and can cause the tube to adhere to the tire. I leave it on the patch until the next repair where it usually falls off.
