I bought these bulbs for my 2011 E350W, which takes H7 bulbs, although the Amazon website said the H11 bulbs are compatible with my car:

So far, I can't even remove the old ones, they are stuck in pretty well, so I will take it to a shop.

However, I want to make sure I have any needed adapters or wiring harnesses first. Can you please tell me what is needed, or are these direct plug and play?

Thanks much!

BTW, I really appreciate the responses from you all willing to help a newbie like me! This is my first Mercedes and I'm trying to learn the ropes.

 

I have had a Morimoto HID kit (from retrofit resource) in my 2011 for several years now, but as I recall the bulbs are held in with metal clips. Are you trying to twist the bulb out? That won't work, the clips need to be squeezed and pulled out with the bulb.
HID

H7 are lo beam bulbs, H11 are fog light bulbs.
Also, depending on the size of the fan housings on those led bulbs you may need to modify the plastic access cap at the back of the headlight housing, if you just cut a big hole however (as most shops seem to do) it's a great way for dirt and moisture to get into the housing.

Most times you can't use the original factory bulb retaining clips without having to cut them to be able to slip them over the new bulb harness plug. Aftermarket are available that are in more of a u-shape with an open slot to fit on the wire. I did this as I did not want to mess up the original clips in case I went back to original.

In addition, the bulbs need to work with the CANBUS system in the car otherwise you will get bulb out error readings. Whatever you get needs to have the proper CANBUS connectors (they are essentially built in resistors). Most led kits don't require a relay harness, but most HID kits do.

Lots of debate on using led and hid, I don't want to get into that but be aware that in many cases the led may give a whiter but not better light if that makes sense. 5.5-6k lighting spectrum level is about max for white light, anything over tends to get blueish. Halogen are generally in the 2.5 to 3.5k range I believe, thus the yellower lighting level.

There are a number of factors mentioned here that you may want to consider and resolve before going further. If you are not familiar with the car or the installation it may be worthwhile doing more research first.