There is a reason it is hard to grasp what Buddhism is as a religion. It is split up into three main branches called Theravada, Mahayana and Vajrayana Buddhism. These three vary a lot in religious philosophy which is one reason that it is hard to grasp a singular concept called Buddhism. Secondly, Buddhism has a tendency to incorporate local folk religion wherever it spreads, so you basically get different local composites of a specific tradition of Buddhism + the local folk religion.
If you want to understand Buddhism you need to study Buddhist philosophy and try to understand the concepts taught by Siddharta Gautama himself. Which basically means you need to understand the four noble truths:
1) Life is suffering
2) Suffering is caused by attachment
3) The cessation of suffering is attainable
4) There is a path to the cessation of suffering.
The eightfold path:
Which is the right:
view, intention, speech, action, livelihood, effort, mindfulness and concentration.
And the five skandhas which are five phenomena that serves as objects of attachment and basics for our sense of self:
1) Form
2) Sensation
3) Perception
4) Mental formation
5) Consciousness
The insight being that there really is no such thing as an eternal substance, no such thing can exist. Which results in the idea of impermanence. Not even humans are an eternal substance, but rather an elusive changing constellation of physical forms, sensations and perceptions.
Even the gods change in Buddhism and also they are impermanent.
The three problem is ignorance, greed and desire. The ignorance of the true reality of no permanent substance leads to a greed and desire for clinging to these objects only to suffer when they inevitably change.
It is a complex philosophy and I can not claim to fully understand it. It is a foreign culture filled with concepts foreign to our western culture which means it requires some study to properly understand it. Buy a few good books on it and read some of the central scriptures (although they are not scripture in the sense that the Bible is scripture to Christians), it really is not harder than that.
I find Buddhism very fascinating and have an interest in it as a part of a general interest in religion and in east-Asian cultures.
Besides the basic components listed here and the understanding of those it really is not a religion of dogma like Christianity, it is more of an experiential religion and meditation and mindfulness are the true sources of learning.