can you help me understand the inputs for this bayes theorem calculator for my scenario?

I'm trying to calculate the probability of delivering a website based on the conditional delivery of an underlying database. I entered some inputs into this online Bayes Theorem calculator:

https://bit.ly/2IIkM5f

For this scenario:

• Database Delivery has a marginal probability of 0.80
• Website Delivery has a marginal probability of 0.90.
• Website Delivery depends on underlying Database Delivery

The first 2 inputs appear to be straightforward: "Update probability of Website Delivery based on Database Delivery." That's exactly inline with what I want to know.

The 4th input appears to request the probability of Database Delivery given Website Delivery. Website Delivery depends on Database Delivery but Database Delivery has no dependency on Website Delivery so I guess that I should just input the standard marginal probability for Database Delivery into this input right?

The 5th input has a "return key" looking symbol that I'm not familiar with. I googled it and it seems to represent "not" but I'm not clear on what that means in the context of this input.

These are things that I'll need to understand in order to use this calculator in a valid and meaningful way. Can you provide any insight for these questions?