Debbie,
Place the dry starter in a plastic container and add 1 cup of warm water and 1 cup of whit/unbleached flour. Keep the starter between 70 and 75.
Plastic container-Use only plastic, or wood. The enzimes in the starter react to metal A large inexpensive juice pitcher with the lid that fits down inside the pitcher and can be positioned so that it is open or strain or closed. ALWAYS allow for the starter to double in bulk.
Keeping warm- I have a microwave above the stove top. Under the microwave is the fan and light for the stove and oven. The microwave, overnight, with the light on is the best place for my starter. Try putting it in the oven, propping the door open with a wooden spoon so that the light stays on for 8 to 12 hours. It may take a couple of days for this starter to become active again.
The best book is from Ruth Allman. I will locate mine for more details. I like hers best because the recipes require sourdough starter as the main ingredient and not a passing thought and the recipes are short and simple.
Enjoy, Julie