Here are some additional letters that you need to learn.
ㄱ set
ㄱ is the letter you already learned (k)
ㄲ is a new letter. It is two ㄱ's placed side by side. It sounds very similar to the original 'ㄱ' but it is more forced at the beginning of the pronunciation. It is Romanized as 'kk'
ㅋ is also a new letter, this also sounds very similar to the original 'ㄱ' and is Romanized as 'k'
ㅂ set
ㅂ is the letter you already learned (b)
ㅃ is a new letter. It is two ㅂ's placed side by side. It sounds very similar to the original 'ㅂ' but it is more forced at the beginning of the pronunciation. It is Romanized as 'bb'
ㅍ is also a new letter, this also sounds very similar to the original 'ㅂ' but is Romanized as 'p.' It is closer to a 'p' in English, but, even in English, B and P are VERY similar (say box and pox and try distinguishing the two)
ㅈ set
ㅈ is the letter you already learned (j)
ㅉ is a new letter. It is two ㅈ's placed side by side. It sounds very similar to the original 'ㅈ' but it is more forced at the beginning of the pronunciation. It is Romanized as 'jj'
ㅊ is also a new letter, this also sounds very similar to the original 'ㅈ' but is Romanized as 'ch.' It is closer to a 'ch' in English, but, even in English, J and CH are VERY similar (say char and jar and try distinguishing the two)
ㄷ set
ㄷ is the letter you already learned (d)
ㄸ is a new letter. It is two ㄷ's placed side by side. It sounds very similar to the original 'ㄷ' but it is more forced at the beginning of the pronunciation. It is Romanized as 'dd'
ㅌ is also a new letter, this also sounds very similar to the original 'ㄷ' but is Romanized as 't' It is closer to a 't' in English, but, even in English, T and D are VERY similar (say task and dask and try distinguishing the two)
ㅅ set
ㅅ is the letter we already learned (s)
ㅆ is a new letter. It is two ㅅ's placed side by side. It sounds very similar to the original 'ㅅ' but it is more forced at the beginning of the pronunciation. It is Romanized as 'ss'
