If you want a simple explanation of bloom filters:

To add to filter:

1) Get multiple hashes of the data. You can use the same hash function and increment the data each hash, or use multiple hash functions. You can do any amount of hashes from 1 to infinity, each filter size and dataset size has a sweet spot.

2) Mod (remainder) each hash by the filter size. The filter size can be any size, 1 to the maximum hash from your function[s]. The larger the filter, the more accurate the results, but a filter larger than your dataset is obviously useless.

3) Set each bit at the locations (from step 2) in the filter to 1.

To check filter:

1) Do steps 1 & 2 from previous procedure.

2) Check each location in the filter. If all locations are 1, the data might be in the filter. If any of the locations are 0, the data is definitely not in the filter.