I am enrolled in community college, majoring in photography. I currently do head shots but I want to do vintage(ish) portraits of families of say 4-5 people. I have a studio set up with a vintage sofa like the one in the following image, and I have a 10x10 damask backdrop. How do I get it all in the photograph? I am working with a 50mm 1.8 lens.
Try moving back to fit the composition you want, use a tripod, and stop that 50 down. The blur and general lack of sharpness may be due to shooting wide open at f/1.8. If your composition calls for bokeh of the type that f/1.8 provides, consider calculating a precise dof and positioning your subjects very carefully, keeping in mind that your range of acceptable sharpness will change with the distance to your focal point, at any aperture.
eg. With an aps-c sensor, 50mm at f/1.8, a focus point 7 feet away will yield about 5 inches of acceptable sharpness. Try to keep your subjects' eyes in that zone of sharpness while respecting your composition. Stopping down a touch will help, if you don't need the wide open bokeh.
edit: check that you're not missing focus, too. tripod helps for manual focus, especially because you are in complete control of your environment.
50mm should work perfectly fine, an 85mm might be a bit too long assuming the photographer was on the same (level) ground and of average height. Judging by the example photo you provided it appears that the angle of view is relatively close, with a small aperture (maybe f/8-f/16 at 50mm) when looking at the bokeh. The size of the camera sensor would affect this, so I'm comparing to full frame camera. If a longer lens was used, the person would likely need to stand on something otherwise the horizon would start to come into view, as the perspective is slightly downward in the example.
You could also use a wider lens (e.g., 35mm) with larger apertures if you don't have enough room to move back for the desired composition. Just be aware that lens distortion might become a factor if you have straight lines anywhere, or subjects near the edges of the frame; most wide angle lenses tend to be softer toward the edges.
With regard to the lighting, it looks like it was an overcast day as there are no strong highlights on the people. There are also no discernible shadows on the ground except for under the sofa, and the plants do not appear to have strong contrast. You could use some sort of diffuse (a bed sheet held overhead or to the side), but it might look weird with the rest of the scene showing stronger shadows. The cloud-diffused sun appears to be above and slightly behind the subjects. There was probably some reflected lighting from in front and to the side of them as well as they are very evenly lit.
Seeing that this is a studio shoot. I think the most important consideration is the backdrop you will be using and the distance have available in studio to distance backdrop from subjects.
The charm of you example image comes from the fact that the background "surrounds" the subjects. see the grass in front and flowers next to bench. Using natural looking backgrounds will like obvious fakes with this type of shot layout. Safest would be neutral infinity background. in this case aperture will not be a priority to blur the background much, so shoot at the sweet spot for your lens. have the background as far away as your lighting and space will allow.