Not too bad a first effort and with practice you'll do much better soon. It looks like you used Silver. I like to start my students on brass/bronze. it's cheaper, learning heat control can be more critical (as things are hotter overall), the slower flow of brass/bronze makes it easier to "keep up" with what's going on, it's less critical WRT cleaning and prep work and it's more forgiving of poor fit up.

Your joint looks like the end with the gap had either not been fitted well to start with or the lug end lifted up during brazing. Once the gap grows to a large enough amount no amount of filling attempts will do to fill the gap. You could have tapped down/squeezed down the lug end to close up the gap during brazing, not easy for the newbie though. When I've had a poor fit up (often due to the joint angle being off the lug's angle) I'll sometimes use a hose clamp to hold down the lug tip during the brazing of the majority of the lug, then remove the hose clamp before I flow out to the tip. Really the best advice is to prep and fit the lug/joint better to begin with.

You have left a number of areas on the shoreline with globs of filler remaining. Perhaps from trying to over add filler to fill the gap just mentioned. But not a pretty result and will leave you with a lot of filing to clean up. You can use the flame to help even out the globs after flowing the lug fully. Bring the torch in close to the shoreline and melt just the filler exposed past the shoreline. It will spread out and try to even the globs with the lesser globbed adjacent areas near by. By running the flame around the shorelines the globs melt in and flow out. Sometimes the flux hides the shoreline detail, using the filler rod to rub up against the shoreline can help push flux out of the way so you can see better, but do this at a temp that the flux is still liquid but not hot enough to have the filler rod melt. If there's too much filler you can draw it away from the shoreline and to an area of tube that's going to be cut off or easily gotten at with a file.

I don't see evidence of overheating and the areas that are filled look to be fully filled. Again a good first. Cut this open and confirm the internal fill rate then have another go. Andy.