German grammar is known for being tricky and as for me, adjective endings is one of the most challenging parts of it. So I found this amazing table explaining every bit you should know to fully master them:
...habe ein lingot is an incomplete sentence. correct it would be "ich habe ein lingot" - i have a lingot (habe is 1. person sing) so it does not work if you want to give something away.
you can say: Da hast du ein lingot (resp: Da haben Sie ein lingot if you want to be formal) or better: Nimm ein lingot (take a lingot) (resp: Nehmen Sie ein lingot)
ich habe - i have
du hast- you have (informal sing)
er/sie/es hat - he/she/it has
wir haben -we have
ihr habt - you have (informal plural)
sie/Sie haben - they have / you have (formal sing+ pl.)
You might like my 'explanation' about adjective endings, then: https://www.duolingo.com/comment/21195697
Also, note that in that table the example about the tiger and the lion uses the wrong verb form. It should be beißt rather than bisst, which is a preterite form belonging to a different pronoun.