The active contact card is indicated in the side bar as a sub-tab of the Address Book tab. It is also indicated in the menu bar where you can find the functions that effect the contact card.
The functions available for the contact card are self explanatory. How an email is processed, either your default email client or a web based email client like gMail will depend on your settings in the Application Options section.
If you want to write notes about your contacts, you just go to the top of the window and select the Notes tab. If you want to date and time the notes, just click on the small calendar icon to the left of the screen, and it will insert the date and time into the text field. You can also store a custom usage license for your contact in the notes section of the contact card. Whenever you create a new job for the contact the custom usage license will be imported.
Next to the Notes tab, is the Groups tab. This basically allows you to place people in a certain groups to keep your contacts organized for locating and mass communication.
Next is the Jobs tab which displays a list of all the jobs associated with the contact. The link to jobs within Blinkbid is based on a unique contact ID. This matters in that if you delete all your contacts and re-import them, all the links will be broken. This is a holdover from previous versions fo Blinkbid and we're working on a viable way to link jobs to contacts based on name.
If you Delete a contact it does NOT delete the jobs to which the contact is linked. The jobs are an independent section.
Related Contacts is the last tab in the Address Book. Here you can see how your contact is related to other contacts in your address book by company to the met via field. For example if I made a slew of new contacts at the Goodby party, I would enter "Goodby party" in the met via field. Conversely if I met a contact throught my friend Andrew, I could also enter that in the "met via" field. If contact is related in wither of these ways you'll see it displayed in this section.