I am looking to find galaxy spectra of early type elliptical galaxies in the SDSS catalog by the objects name. See: https://dr12.sdss.org/advancedSearch. I dont know how to find out the PLATEID of my objects of interest, e.G. NGC 4125, NGC 4472 (Messier 49) or NGC 4649 (Messier 60), in the advanced search. I have tried to work with the constrains for redshift and sky position, but in the sdss library the objects name never turn up so I dont know if the found spectra are the spectra of the galaxies i mentioned. I am new to working with astrophysical data and the sdss catalogue in particular so please forgive me if this should be approached completely different. Can anyone tell me how to find these galaxy spectra fits files on the sdss website ? I am planning to further work with these fits files in python and extract kinematical parameters.
One thing you might try doing is to use the SkyServer Navigate interface to see if the object was imaged by SDSS. Enter the name in the "name" box in the upper left and then click on the "Resolve" button. If an image with the galaxy shows up, click on the "Object with spectra" checkbox in the "Drawing options" panel on the left, and red squares will appear for objects with spectra. If there's a red square associated with the center of your galaxy, then there's a spectrum. (You can click on the links on the right-hand side to find out more; there may even be a little graphic of the spectrum you can click on.)
Here's an example for the elliptical galaxy NGC 6066, which does have an SDSS spectrum (as indicated by the spectrum-plot graphic to the lower right):
Something you should be aware of: in many cases, very nearby and luminous galaxies like your three examples simply don't have SDSS spectra. (This is true for your three galaxies, in fact.) Since such galaxies were known to already have plenty of spectra (including redshift measurements), there was little need to get SDSS spectra of them, so they were ignored. So you may end up needing to focus on more distant elliptical galaxies (NGC 6066 has a redshift of 0.034, while your example galaxies all have redshifts $< 0.005$.)