Note that while the focus on this talk was on Civil Registration (from 1864), the site also gives access to some Church Records (Parish Registers) both before and after that date. The coverage is uneven with respect to time and denominations represented and other sites (such as https://registers.nli.ie/) may give better results.
There is no need to create an account at the site to search or download records; but you are required to enter "a name" each time you use the site. It does not need to be your real number (or even the same name each time). The site does not keep a history of what you searched or what you found (that is your responsibility -- to avoid duplication).
Digitisation of the records is not yet complete (but is on-going). At present the coverage is Births 1864-1918 Marriages 1864-1943 Deaths 1878-1968. It is recommended that you check regularly to find which early records have been added recently.
As with most Irish research, it is almost essential that you know a location to search (in this case, the name of the Registration District) as well as a name and time period. There are several tools that can help you to identify possible candidates (ie a list of Districts within a county, or the larger places that enclose a townland). Although you must remember that the names of townlands are duplicated across Ireland in the same way that Australians reused the same street and suburb names in widely-spaced towns.
When you get a search result there will be a set of filters for place and time (at the left of the screen) that you can use to reduce the size of the list. When you have identified one or more of them as worthy of further investigation, click on the person's name. (Caution: The link will change colour when the mouse cursor is over it and may become invisible, but click anyway.) The next screen does not provide any new information but does give two hyperlinks.
Once you have a pdf of the Register page saved to your local machine, you can enlarge and trim the relevant part of the image and make a transcription of the information. But remember that the spelling of names and/or places might not be quite as we expect today.
Dea-chuardach