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4 medium white onions
1/2 cup canning salt
3 cups vinegar
2 cups sugar
1 teaspoons celery seed
1 teaspoons turmeric
2 Tbsp mustard seeds
Slice unpeeled cucumbers 1/8-1/4 inch thick. Slice peeled white onions 1/8 inch thick.
In a large stockpot, arrange cucumbers in layers, sprinkling each layer with canning salt. Let stand for 2 hours; rinse in cold water and drain in colander.
Bring vinegar and remaining ingredients to a boil. Add vegetables; bring to a boil again and boil for 5 minutes.
Pack into hot, sterilized jars, leaving 1/4 inch headspace. Adjust caps. Process in a boiling water bath canner for 10 minutes.