Easy repair, but Robert has steered you correctly, if your not familiar, best left the the "pros".
Have both springs "rebuilt", with new center pins and bushing while your at it. Is the wedge plate that holds the shock mount cracked or split at all, or did it just spit out. Looks to me like it just spit out.
Actually it looks to me as if the u-bolts came loose, then you hit (pot hole, whatever) something hard enough to shove the whole axle back, off the center pin. This would cause serious handling and steering issues.
Luckily a good spring/suspension shop should be able to have you back on the road in a day, maybe two if they have to order parts.