Let's use the Intro of the song to get our feet wet. We've got our C Major chord and each of those slashes is one down strum (one beat) and you will play it four times. Those four strums will equal one whole measure. So far, you've already done that. However, before switching to Em like before you have to strum C four more times (or another measure). In total we have two full measures of strumming C, or 8 downward strums of C, but it's best to get used to thinking of it as two groups of four. You should count it 1-2-3-4, 1-2-3-4. Now we can switch to Em, and looking ahead, you've probably noticed you strum Em for another two measures. To play the entire intro, you strum C for two measures then Em for two measures, then repeat all of that once more. There's the intro in all of its glory!
The verse of Eleanor Rigby is still only C and Em, you'll just have to count and pay attention to how many measures of each chord you play. WATCH OUT! Measures 9 and 14 have two beats of C and two beats of Em.
The chorus is very fun, this is where you get the most movement during the song. You will play one measure each of Em7, Em6, C, & Em. You'll see the genius of the Beatles here. Em7, starts with your index finger on the 3rd fret, then Em6 on the 2nd fret, C on the 1st fret, then no fingers for Em. It literally just walks itself down! Very cool.
Once you have completed the three sections, (Intro, Verse, & Chorus) the rest of the song continues in this order: Verse, Chorus, Intro, Verse, Chorus. That is it. Other than maybe getting a little lost in the sea of Em's in the verse, it's actually a fairly simple arrangement.
Now that you have completed the entire song of Eleanor Rigby, you will need to listen to it multiple times. Listening to the song regularly will not only help you memorize it, but help you internalize it, and know it on a much deeper level. Oh! Make sure for as much as you listen to the song passively, like in a car, running, doing chores, try listening to it "actively." For example, with headphones on, sitting down, and no other distractions. That one simple act is a huge part of becoming a better player.